Chokes have been used for decades in oilfield operations to reduce the fluid pressure of high pressure flowing fluids. The life of a choke is significantly reduced by cavitation and/or flashing that occurs when high pressure fluids are decompressed. Cavitation occurs when the pressure of a fluid drops below its vapor pressure and then recovers to above its vapor pressure. The desired pressure drop across a choke can cause cavitation, resulting in voids, such as small bubbles, in the fluid. When the pressure recovers to above its vapor pressure near the outlet, the voids can implode and collapse. The repetitive implosions near metal surfaces of the outlet can cause material loss.
Various attempts have been made to reduce cavitation and flashing in chokes. Multiple stages can be used to spread the overall desired pressure drop across the stages to help the pressure remain above its vaporization pressure as the pressure is reduced. Some of the challenges of multistage chokes are the price of the choke, which may be 10-15 times greater than a single stage choke, the short wear life of the choke when solids are present, and clogging of very fine labyrinth passages within a choke.
Multiple concentric cages or multiple stacked disks may be used to define a torturous path through a choke. Stacked disks are disclosed, for example, are made by Weir Power & Industrial in the USA under the brand X-Stream choke. However, the cost of manufacturing multiple disks with varying diameter staggered cylinders extending from the disk face is a significant drawback to these designs.
Therefore, there remains a need for an improved system and method for a multiple stacked disk choke that can be efficiently produced.